Development of a quantitative vancomycin immunoassay for the Abbott AxSYM analyzer.

A novel fluorescence polarization immunoassay for vancomycin on Abbott AxSYM analyzer is described. The immunoassay allows for the accurate quantification of vancomycin in the presence of the crystalline degradation product (CDP). It displays dilution linearity from 1.0 microg/ml to 100.0 microg/ml, coefficients of variation ranging from 2.94% to 4.26%, recovery from 98% to 105%, and a sensitivity of <2.0 microg/ml. The assay demonstrates no cross-reactivity to crystalline degradation product, and to commonly-prescribed and over-the-counter drugs, as well as a minimum interference from endogenous substances.

Abbott AxSYM Vancomycin II assay: multicenter evaluation and interference studies.

The authors evaluated the performance characteristics of the Abbott AxSYM Vancomycin II immunoassay in sera of patients with (n = 93 samples) and without (n = 327 patients) renal dysfunction. Correlation of vancomycin measurements with the Abbott AxSYM Vancomycin, Abbott TDx/TDxFLx, Syva enzyme-multiplied immunoassay technique (EMIT), DuPont automated chemistry analyzer (ACA), and high-performance liquid chromatography methods showed acceptable correlation as indicated by: slope values >0.95, r-values >0.97, y-intercepts <1.7 microg/ml, and S(y/x) ranging from 9% to 15% of the average vancomycin value. The AxSYM Vancomycin II assay showed acceptable correlation with AxSYM vancomycin, TDx/TDxFLx, and high-performance liquid chromatography methods in 93 samples from patients with renal dysfunction. This monoclonal antibody-based assay showed no apparent interference from the presence of human antimouse antibody (HAMA) or the microbiologically inactive vancomycin crystalline degradation product (CDP). The authors conclude that the AxSYM Vancomycin II assay showed satisfactory agreement with other methods tested in this study.

Surgical treatment of complete acromioclavicular separations.

A retrospective study of fifty-two patients (48 cases followed up), with Allman-Tossy grade III acromioclavicular separations, who were treated with coracoclavicular reconstruction by Mersilene prosthetic substitute (Mersilene tape with polyester suture, 5 mm wide, 30 cm, Ethicon), was carried out. The average follow up was 38 months, with the longest being 10 years, and the shortest being 8 months. The average age of the patients was 32 years, with a range from 20 to 62 years. Two groups were divided by age. Although the younger age group showed better results than the elder one in pain, range of motion and return to previous occupation or sports, the overall outcome was satisfactory in 41 of 48 (86%) followed patients. For the grade III acromioclavicular separation patients, surgical reconstruction with Mersilene looping provides a reliable result including use of the arm for sports or repetitive work.

Excessive urinary excretion of zinc in drug addicts: a preliminary study during methadone detoxification.

Random samples of urine from control subjects, and subjects treated with methadone (an agonist of morphine) for drug addiction, were analyzed for calcium and trace elements zinc and copper. The following differences (based on creatinine) were observed between the two groups: Calcium excretion did not show any significant differences between the two groups (146 mmg/g creatinine vs. 135 mg/g creatinine vs. 33 +/- 3 micrograms/g creatinine in controls). However, the excretion of copper in drug addicts diminished (23 +/- 3 micrograms/g creatinine in controls; p < 0.05), while that of zinc was excessive (600 +/- 50 micrograms/g creatinine vs. 300 +/- 30 micrograms/g creatinine in controls; p < 0.001). The ever increasing link between zinc and immunity and the fact that drug addicts are susceptible to various infections such as hepatitis and acquired immuno deficiency syndrome raises concern about the excessive urinary loss of zinc in this group and calls for further investigations such as balance studies and intervention if necessary.

Automated determination of human choriogonadotropin by use of microparticle capture analysis.

We evaluated a new microparticle enzyme immunoassay (MEIA) for human choriogonadotropin (hCG) in serum. This hCG assay is fully automated for the Abbott "IMx System," which has a dynamic range extending to 100,000 int. units/L. We tested 321 patients' sera, with hCG values ranging between 0 and 196,000 int. units/L by both the IMx hCG (y) and the Hybritech Tandem-E hCG (x) assays. Results correlated well (r = 0.972, slope = 0.87, y-intercept = 0.7). The IMx hCG assay is sensitive (0.21 int. units/L) and precise (CVs 2.4-8.7% for various hCG concentrations). No carryover to subsequent specimens was observed when specimens with values up to 10(6) int. units/L were tested, nor was any high-dose "hook" effect noted. The IMx hCG assay, which is specific for intact hCG molecules, is rapid (one to six samples in 17 min) and is a valid automated alternative to enzymatic and radioisotopic methodologies.

Liquid-chromatographic determination of urinary pentachlorophenol.

We developed and evaluated a simple liquid-chromatographic method for urinary pentachlorophenol (PCIP) determination with ultraviolet detection. PCIP and the internal standard (2,3,5,6-tetrachlorophenol, TCP) were extracted with a solid-phase extraction column, and 50 microL of the collected eluate was injected into the chromatograph. The intra-assay and interassay CVs were 6.6% (n = 20) and 7.9% (n = 10), respectively. The analytical recoveries varied from 89% to 96%, with absolute recoveries ranging from 82% to 88%. Thirty urine specimens collected from 30 unexposed individuals were analyzed by the current method, and results were all less than the minimum detection limit, 0.25 mg/L. Results for five specimens from workers who had been exposed to PCIP ranged from 7.0 to 12.4 mg/L. The standard curve was linear to 300 mg/L. This procedure is adaptable to automated analysis, and therefore suitable for monitoring industrial exposure of workers.

Determination of vitamin E in microsamples of serum by liquid chromatography with electrochemical detection.

In this procedure for determination of vitamin E by "high-performance" liquid chromatography with electrochemical detection, 25-microL serum specimens are deproteinized with ethanol. Vitamin E (alpha-tocopherol), its derivatives (beta- and gamma-tocopherols), and the internal standard (delta-tocopherol) are extracted into heptane and the extract is evaporated and the residue reconstituted with methanol before injection into the chromatograph. Within- and between-run CVs for an alpha-tocopherol concentration of 13.6 mg/L were 5.1% (n = 28) and 6.0% (n = 5), respectively. The standard curve is linear to 100 mg/L; the minimum concentration detectable is 0.1 mg/L. Analytical recovery ranged from 99.8% to 104.8%. In 36 specimens collected from apparently healthy subjects who were not taking vitamin supplements, alpha-tocopherol as determined by this method ranged from 4.3 to 9.7 mg/L, from 1.8 to 3.9 mg/L for beta- and gamma-tocopherols. Results by this method (y) and an HPLC-ultraviolet method (x) correlate reasonably (r = 0.81): y = 0.88x - 0.55 mg/L (n = 45). This procedure is adaptable to automated analysis, and the small sample requirement facilitates its applicability to neonates.

Evaluation of a mini-column chromatographic procedure for the measurement of hemoglobin A1c.

An ion-exchange chromatographic procedure is described which facilitates the determination of beta-chain aminoterminal modified glycated hemoglobin. The procedure includes an erythrocyte lysis reagent which eliminates the labile aldimine component (pre-A1c) and a two-stage elution step which separates HbA, 1a + b from HbA1c. This procedure also includes calibrator material which aids in correcting for temperature fluctuations during the analysis. Within-run CV's for samples with HbA1c levels between 4.0% and 13.7% were 1.4 to 3.2%. The between-run CV for an HbA1c control was 5.5%. A comparison of the present test to an ion-exchange HPLC method yielded the equation: HPLC = 0.96 (present method) -0.2% (n = 101 and r = 0.984). Two separate reference range studies yielded comparable results (n = 220/65, mean = 4.77/4.78%, S.D. = 0.68/0.55). Studies with pooled erythrocytes and various lipemic plasmas did not reveal any assay interferences. Various abnormal hemoglobins were studied for their effect on the assay.

Determination of bismuth in urine by atomic absorption with hydride generation.

A procedure for the determination of urinary bismuth by atomic absorption spectroscopy with hydride generation was developed and evaluated. Specimen or standard solutions were mixed with an acid mixture and an antifoam reagent. Sodium borohydride solution was then introduced to the reaction flask in order to produce bismuth hydride. The preliminary reference range for urinary bismuth was found to be less than 17 micrograms/L in 20 healthy control subjects. For patients on medications or medical treatments, bismuth levels varied from 5 to 1,460 micrograms/L. The minimum detection limit was found to be 2.5 micrograms/L and the procedure was linear to 250 micrograms/L. The intra-assay and interassay coefficients of variation at the level of 21 micrograms/L were 4.0 (N = 33) and 4.1% (N = 19), respectively. Average bismuth recovery was 97.7% for concentrations ranging from 25 to 100 micrograms/L. This procedure is simple, fast, and sensitive enough to detect levels well into the reference range. Preliminary studies also indicate this method can be used for serum bismuth determinations.